1. Field of the Invention
The invention relates in general to the field of pulmonary disease treatments, and specifically to a bronchoscopic method of performing lung volume reduction surgery using an obstruction or one-way valve.
2. Description of the Related Art
The lungs deliver oxygen to the body by directing air through numerous air passageways that lead from the trachea to respiratory bronchiole to small sacs called alveoli. These alveoli are generally grouped together in a tightly packed configuration called an alveolar sac, and surround both alveolar ducts and respiratory bronchiole throughout the lung. The alveoli are small, polyhedral recesses composed of a fibrillated connective tissue and surrounded by a few involuntary muscular and elastic fibers. These alveoli inflate and deflate with the respiration of air. Oxygen and carbon dioxide are exchanged through the ultra-thin walls between alveoli and capillary sized blood vessels.
During inhalation, as the diaphragm contracts and the ribs are raised, a vacuum is created in the chest, and air is drawn into the lungs. As the diaphragm relaxes, normal lungs act like a stretched balloon and rebound to the normal relaxed state, forcing air out of the lungs. The elasticity of the lungs is maintained by the supportive structure of the alveoli. This network of connective tissue provides strength to the airway walls, as well as elasticity to the lungs, both of which contribute to the lung's ability to function effectively.
Patients with chronic obstructive pulmonary disease or emphysema have reduced lung function and efficiency, typically due to the breakdown of lung tissue. Lung tissue and alveoli are destroyed, reducing the supportive structure of the airways. This reduction in strength of the airway walls allows the walls to become “floppy,” thereby losing their ability to remain open during exhalation. In the lungs of an emphysema patient, the walls between adjacent alveoli within the alveolar sac deteriorate. This wall deterioration is accelerated by a chronic inflammatory state with the production of mucus in the lungs. Although the break down of the walls of the alveoli in the lungs occurs over time even in a healthy patient, this deterioration has greatly accelerated in people with emphysema so multiple large spaces with few connecting walls replace the much smaller and more dense alveoli in healthy lung tissue. When many of the walls of the alveoli have deteriorated, the lung has larger open spaces (bullae or air cavity) and a larger overall volume, but has less wall tissue to conduct gas exchange.
In this diseased state, the patient suffers from the inability to get the air out of their lungs due to the loss of elasticity of the lungs as well as the collapse of the airways during exhalation. Heavily diseased areas of the lung become hyper-inflated. Within the confines of the chest cavity, this hyper-inflation restricts the in-flow of fresh air and the proper function of healthier tissue, resulting in significant breathlessness. Thus, the emphysematous patient attempts to take in a greater volume of air to achieve the same amount of gas exchange. With, severe emphysema, when patients take in as much air as their chest cavity can accommodate, they still have insufficient gas exchange because their chest is full of non-functional air filling large cavities in the lungs. Emphysema patients will often look barrel-chested and their shoulders will elevate as they strain to make room for their hyper-inflated lungs to work.
A wide variety of drugs are available for treating the symptoms of chronic obstructive pulmonary disease, but none are curative. Chronic bronchitis and emphysema are typically treated with antibiotics and bronchodilators. A large number of patients are not responsive to these medications. In selected severe emphysema cases, lung volume reduction surgery (LVRS) is performed to improve lung efficiency and to allow the patient to improve breathing function and quality of life. In lung volume reduction surgery, the most diseased portion of an emphysematous lung having a large amount of alveolar wall deterioration is surgically removed. LVRS is performed by surgically entering the chest cavity then stapling off and resecting the diseased portion(s) of the lung(s). This allows the remaining healthier lung tissue to inflate more fully and take greater advantage of the chest mechanics to inhale and exhale. Because there is more air and more gas exchange in the healthier portion of the lung, lung efficiency is improved and patients feel better.
Traditional lung volume reduction surgery is an invasive procedure requiring surgically entering the chest cavity and removal of lung tissue. This surgery has substantial risks of serious post-operative complications, such as pneumonia, and requires an extended convalescence. There have been more recent attempts to achieve lung volume reduction through minimally-invasive procedures. For example, U.S. Pat. Nos. 6,293,951 and 6,258,100 to Alferness et al. describe methods of collapsing a lung portion by obstructing an airway. U.S. Pat. No. 6,488,673 to Laufer et al. describes a method of increasing gas exchange of a lung by causing tissue damage within a diseased airway in order to cause the airway to remain open. U.S. Patent Application Publication No. 2001/0051799 to Ingenito teaches another method of non-surgical lung volume reduction that involves injecting a polymerizable sealant into a diseased lung section. Notwithstanding the benefits of the above methods, minimally invasive lung volume reduction may be performed utilizing other advantageous methods.